文件类型转换错误

原文请移步

 MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest)(request);

空文件上传会出现类型转换错误
做一步处理

MultipartHttpServletRequest multipartRequest =null;
if (request instanceof MultipartHttpServletRequest) {
multipartRequest = (MultipartHttpServletRequest)(request);
}

先判断httpRequest 是否含有文件类型 ,若含文件，则将httpRequest 转换为MultipartHttpServletRequest类型。